Safety lock loose-leaf ring binder mechanism

ABSTRACT

A loose-leaf binder mechanism is disclosed which includes a case containing a pair of pivotally mounted hinge plates each carrying a series of spaced prongs. The hinge plates are movable between two alternate positions. In one of these positions the prongs are closed together to define a loose-leaf sheet retaining loop and in the other position the prongs are spread apart. The binder mechanism also includes a specially constructed operating lever to move the hinge plates between the two positions. One portion of the lever is selectively moveable along a predetermined arcuate segment of the path of movement of the lever into a wedged-in position between the case and hinge plates to lock the prongs in closed position. The lever is specially constructed so that it can be moved while wedged between the case and hinge plates to a safety-lock position such that any point of contact between said one portion and the case is advantageously disposed longitudinally inward of any point of contact between said one portion and the hinge plates and so that it cannot be moved inward past the safety-lock position out of wedged-in relationship between the case and hinge plates.

United States Patent [1 1 Michaelis et al.

[451 May 20, 1975 SAFETY LOCK LOOSE-LEAF RING BINDER MECHANISM [75] Inventors: Jack H. Michaelis, Elmhurst; Frank J. Malcik, Berwyn, both of I11.

[73] Assignee: Swingline, lnc., Long Island City,

[22] Filed: Feb. 1, 1973 [2]] Appl. No.: 328,783

Primary Examiner-Jerome Schnall [57] ABSTRACT A loose-leaf binder mechanism is disclosed which includes a case containing a pair of pivotally mounted hinge plates each carrying a series of spaced prongs. The hinge plates are movable between two alternate positions. In one of these positions the prongs are closed together to define a loose-leaf sheet retaining loop and in the other position the prongs are spread apart. The binder mechanism also includes a specially constructed operating lever to move the hinge plates between the two positions. One portion of the lever is selectively moveable along a predetermined arcuate segment of the path of movement of the lever into a wedged-in position between the case and hinge plates to lock the prongs in closed position. The lever is specially constructed so that it can be moved while wedged between the caseand hinge plates to a safetylock position such that any point of contact between said one portion and the case is advantageously disposed longitudinally inward of any point of contact between said one portion and the hinge plates and so that it cannot be moved inward past the safety-lock position out of wedged-in relationship between the case and hinge plates.

6 Claims, 14 Drawing Figures PMENI HAYZO 1.97s 7%. 884, 586

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FIG. 20

SAFETY LOCK LOOSE-LEAF RING BINDER MECHANISM BACKGROUND OF THE INVENTION This invention relates generally to loose-leaf binders and more particularly to loose-leaf binder mechanisms of the type which are commonly known as ring binders. In construction such binders include an elongated case or cover containing a pair of pivotable elongated hinge plates each of which carries a series of spaced apart prongs. Each prong on one hinge plate is aligned with a prong on the other hinge plate. The hinge plates may be pivoted relative to each other between two positions. In one of these positions the aligned prongs engage each other to form a closed loose-leaf sheet re taining loop; and in the other position each pair of aligned prongs is spread apart to permit removal or insertion of loose-leaf sheets. While the prongs can be used as levers to move the hinge plates between the two positions, such binders commonly include separate lever-type actuating means for pivoting the hinge plates between the open and closed position as exemplified in the following U.S. Pat. Nos. 1,787,956, 1,841,793,

1,868,793, 1,896,838, 1,896,839, 1,913,700, 1,927,113, 2,013,552 2,041,168, 2,498,902, and 3,101,719.

One problem associated with loose-leaf binders of the type described is the possibility that the prongs may be unintentionally opened during use. This may happen, for example, by dropping a filled binder causing the hinge plates to be jarred from closed to open position. In situations where the binder is stored in inverted position with the loose-leaf sheets suspended or hanging from the loop defined by the closed prongs, the weight of the loose-leaf sheets may tend to pry the prongs apart and, in some cases may even cause complete opening of the prongs. To prevent accidental or otherwise unintentional opening of the prongs, a means for releasably locking the prongs in closed position is required. Many heretofore known loose-leaf ring binders have been constructed with various forms of locking means as is exemplified by the following U.S. Pat. Nos. 2,061,676, 2,105,235, 2,950,719, 3,077,888, and 3,098,490. The most pertinent of these U.S. Patents relative to this invention is U.S. Pat. No. 3,098,490 to Wance which discloses a construction where a portion of an actuating lever is wedged between the hinge plates and case to lock the prongs together.

The present invention was conceived in an effort to construct a relatively inexpensive, reliable and easy-touse locking ring binder mechanism. This effort has successfully resulted in a novel and unobvious improved ring binder mechanism which in addition to combining the locking and actuating functions in a lever-type actuator also combines a unique and novel safety lock feature in the lever-type actuator to prevent accidental release of the lock. The construction of this triplefunction lever-type actuator is summarized in the immediately-following section of the specification and described in detail with respect to the presently preferred embodiment shown in the drawings in the remaining portion of the specification following the summary.

SUMMARY OF THE INVENTION In accordance with the teachings of this invention, an improved locking-ring loose-leaf binder mechanism is provided; and, moreover, one which is exceedingly simple in construction with very few moving parts easy and relatively inexpensive to manufacture and assemble and dependable in operation. As in conventional ring binders, the binder of this invention includes an elongated case or cover within which a pair of resilient elongated hinge plates are pivotally mounted with the pivot axis of each extending longitudinally along its outer edge; the inner edges of the hinge plates being disposed in abutting relationship for all angular positions of the hinge plates. Each hinge plate, as in known constructions, carries a series of longitudinally spaced apart prongs with each prong on one hinge plate being aligned with a prong on the other hinge plate. The hinge plates are selectively movable between an inwardly bowed position .and an outwardly bowed position. In the former position, the hinge plates extend inwardly of the case with their surfaces mounting the prongs facing away from each other; each pair of aligned prongs being th'us spread apart to permit insertion and removal of loose-leaf sheets. 1n the latter position the hinge plates extend outwardly of the case with their prong mounting or carrying surfaces facing each other; each pair of aligned prongs thus engaging each other to define a closed loose-leaf sheet retaining loop. Finally, an actuating means is provided for moving the hinge plates between the two described positions.

The improvemnet of this invention resides in the actuating means. According to this invention the actuating means comprises a pivotable lever member or element engaging the hinge plates, hinge plate depressor means responsive to movement of the lever for moving the hinge plates from the inwardly to outwardly bowed position and hinge plate lifting means also responsive to movement of the lever for moving the hinge plate from the outwardly bowed position to the inwardly bowed position. The lever is, more particularly, operable upon being pivoted in one direction through one predetermined arcuate segment of its path of movement to apply an outwardly directed force on the inwardly bowed hinge plates with enough leverage to move them through the coplanar position to the outwardly bowed position. Upon pivoting of the lever through the same arcuate segment in the reverse direction, the lever is operable to apply an inwardly directed force to the outwardly bowed hinge plates sufficient enough to move the outwardly bowed hinge plates through the coplanar position back to the inwardly bowed position. Importantly, the lever is so constructed that a portion thereof can, simply by moving the lever into any one of a range of angular positions disposed along another predetermined arcuate segment of its path of movement, be selectively wedged tightly between the outwardly bowed hinge plates and the case to lock the prongs in closed position.

Within the range of wedged-in positions, the lever can be moved between a first position such that an imaginary line interconnecting any point of contact between the wedged-in portion of the lever and the case with any point of contact between the wedged-in portion of the lever and the hinge plates is oriented at an upwardly inclined outwardly extending attitude relative to the case and a second position such that said imaginary line is oriented at an upwardly inclined inwardly extending attitude relative to the case. Finally, the improved actuating means of this invention includes a stop lock means for preventing inward pivotal movement of the lever to any position beyond said second position where its wedgeable portion would cease to be wedged between the case and outwardly bowed hinge plates.

With the construction described, the hinge plates are locked in the outwardly bowed position, the aligned prongs being thereby locked in closed position, at all lever positions where its wedgeable portion is wedged between the case and outwardly bowed hinge plates. And, importantly, by moving the lever from said first wedged-in position described above past the center wedged-in position into the said second wedged-in position described above, an effective safety for the lock is provided making the chances of the locked prongs becoming accidentally jarred open or otherwise unintentionally released virtually non-existent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a loose-leaf book equipped with a loose-leaf binder mechanism according to this invention.

FIG. 2 is a top plan view of the binder mechanism shown in FIG. 1 partially broken away to show the actuating lever in locked position.

FIG. 2a is a view similar to that shown in FIG. 2 but with the actuating lever in open position.

FIG. 3 is a bottom plan view of the binder mechanism shown in FIG. 1 partially broken away to show the actuating lever in locked position.

FIG. 3a is a view similar to that shown in FIG. 3 but with the actuating lever in open position.

FIG. 4 is an end view of the actuating lever.

FIG. 5 is a side elevational view of the binder mechanism shown in FIG. 1 partially broken away to show the actuating lever in locked position.

FIG. 5a is an end view, partially broken away, of the binder mechanism shown in FIG. 5.

FIG. 6 is a side elevation view of the binder mechanism shown in FIG. 1 partially broken away to show the actuating lever in open position.

FIG. 6a is an end view, partially broken away, of the binder mechanism shown in FIG. 6.

FIG. 7, 7a, 7b and 7c are cross-sectional views taken along the line 77 in FIG. 2a showing the actuating lever in the unlocked but closed position, the beforecenter locked position, the center locked position and the past-center safety locked position, respectively.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIG. 1, the loose-leaf binder of this invention includes an elongated case member 1, a pair of elongated hinge plates 2 and 3 each of which carries a series of prongs 2 and 3', respectively, and an actuating lever 4 located at each end of the case member. In the construction shown, case 1 and hinge plates 2, 3 are made of a relatively stiff spring-like metal the purpose of which will become apparent as the description continues. The case 1 and hinge plates 2, 3 may, however, be made of material other than metal provided it is relatively stiff and exhibits spring characteristics. As shown in FIG. 1, the entire assembly is secured to the spine 5a of a typical loose-leaf book cover 5 by means of rivet 6 extending through hinge plates 2, 3 to connect case 1 and book cover 5 together.

Case 1 has a generally arched cross-sectional configuration with the crown of the arch up and with its marginal longitudinal edges 7 being curled under or down to form elongated hinge pockets 8. Each pocket so formed receives the outer longitudinal edge of one of the hinge plates and generally defines the pivot axis for that hinge plate. The inner longitudinal edges of hinge plates 2 and 3 abut each other along their entire length as shown; the hinge plates being retained in abutment along their inner edges at all angular positions by cleats 6b which are formed along the inner longitudinal edge of one hinge plate to overlap the abutting edge of the other hinge plate.

As best shown in FIGS. 2 and 3, each prong 2' on hinge plate 2 is aligned with a prong 3' on hinge plate 3. The hinge plates are movable between two positions. One position is best shown in FIG. 5a where it will be seen that hinge plates 2 and 3 are bowed slightly outwardly of case 1 with their prong carrying or mounting surfaces facing toward each other. In this position each pair of aligned prongs 2', 3 forms a substantially closed loop or ring for retaining loose-leaf sheets appropriately punched with holes to accept the prongs. The other position of the hinge plates is best seen in FIG. 6a. In this position the hinge plates 2, 3 are bowed inwardly of case 1 with their prong carrying or mounting surfaces facing away from each other; each pair of aligned prongs being thereby spread apart to permit insertion or removal of loose-leaf sheets onto or from the sheet retaining loops.

The combined width of the hinge plates 2, 3 is slightly greater than the distance between the pivot axes defined by hinge pockets 8. Movement between the inwardly and outwardly bowed positions occurs without causing disengagement of the inner edges of the hinge plates. That is, the inner edges of the hinge plates abut each other at all angular positions. The hinge plates 2,3 are thus first moved, say, from the outwardly bowed position into a position at which they are disposed in substantially coplanar relationship, the case flexing or distorting somewhat at this point to accommodate the hinge plates as they move through this coplanar position. The hinge plates then continue into the inwardly bowed position by a snap action as the pressure existing at the coplanar position is relieved and the case naturally unflexes into a semi relaxed state. The same motion characteristics occur in moving the hinge plates in the reverse direction from the inwardly bowed position to the outwardly bowed position. Significant pressure, it will be recognized, must be exerted on the hinge plates to move them through the coplanar position; this pressure being applied by the actuating levers presently to be described.

The actuating lever is best shown in FIG. 4 where it will be seen that it includes an actuator portion indicated generally by reference numeral 11 and a trigger portion indicated by reference numeral 12. The binding mechanism shown in the drawings includes two such levers positioned at opposite ends of case 1.

The actuator portion of the lever has a transversely arched body 13 which conforms generally to the arched curvature of case 1. Body 13 extends in generally parallel offset relationship to trigger 12 in the sense that a plane tangentially disposed to the central portion of body 13 would extend parallel to and spaced from the trigger 12. The upper edge 16 of body 13 is also curved or arched transversely widthwise of case 1 with a curvature conforming generally to the curvature of arched case 1. The crown of arched edge 16 and the crown of arched body 13 extend generally in perpendicular directions with respect to each other. As shown,

retaining member connects the trigger 12 and body 13 together. The retaining member 15 includes two sections 15a and 15b disposed substantially perpendicular to each other. Section 15a is connected at one end to body 13 and at the other end to section 15b. As will be clearly seen in a later portion of the description, the section 150 extends from body 13 longitudinally outward of case 1 in closely spaced relationship to the-undersurface thereof for all locked positions of the lever and the section 15b which is situated exteriorly of the case engages a seating surface 15c defined by the end of case 1 to prevent inward pivotal movement of the lever beyond a certain locked position. The spacing between section 15a and case 1 is provided to eliminate any possibility of preventing or restricting proper lever movement due to interference between section 15a and the case 1 as the lever is moved to a locked position. To insure sufficient spacing the end portion of case 1 is formed with a recessed area 15d located directly over the path of movement of section 15a into the case during movement of the lever to locked position.

Depending from each end of the lower edge 17 of body 13 is a leg element 14 the tip 14a of which is bent toward trigger 12 to lie in a plane which intersects a plane lying tangent to the body 13 at the junction of each leg element. As best shown in FIG. 3, these leg elements engage notches 18 formed in the outer edges of hinge plates 2, 3. The corners 14b between leg elements 14 and lower edge 17 contact the hinge plates within notches 18 to define the fulcrum points of the actuating lever for one arcuate segment of the path of movement of the lever as will be more fully explained hereinafter.

The lower edge 17 of body 13 carries a centrally located T-shaped lifting element 19 which is bent slightly toward trigger 12. The stem 20 of lifting element 19 extends. through an opening 21 defined by a pair of aligned notches formed along the interface between the inner edges of hinge plates 2, 3. As best seen in FIGS. 5 and 5a the cross piece 23 of lifting element 19 engages the undersurface of hinge plates 2, 3 at a point which, in order to provide adequate leverage, is located longitudinally inward of the pivot axis of the actuating lever during movement of the hinge plates from the outwardly bowed position to the inwardly bowed position; this pivot axis being defined by an imaginary line extending between the fulcrum points which, as previously mentioned, are defined by the points of contact between corners 14b of leg elements 14 and hinge plate notches 18.

.The lower edge 17 of body 13 also carries a pair of lug elements 24 which are bent slightly toward trigger portion 12. One lug element is located on one side of lifting element 19 at a point located approximately midway between it and the respective leg element on that side of the lifting element; the other lug element being similarly situated on the opposite side of the lifting mem ber. Lug elements 24 engage the upper surface of hinge plates 2 and 3; the points of contact therebetween defining the fulcrum points for the lever for another arcuate segment of the path of movement of the lever. Namely the points of contact between lugs 24 and the hinge plates define the lever fulcrum points in moving the hinge plates from their inwardly bowed position to their outwarly bowed position and in locking the hingeplates in their outwardly bowed position all of willbecome abundantly clearin the following portion of the specification which describes the operation of the binder mechanism of this invention.

The operation of the binder mechanism thus far described can be best described by starting with the hinge plates in their inwardly bowed position as shown in FIGS. 6 and 6a. In this position, as was previously mentioned, the aligned prong pairs 2', 3' are spread apart and the arched body 13 of actuator portion 11 of the actuating lever is sandwiched between the inwardly bowed hinge plates and the arched undersurface of the case with the trigger portion thereof in a generally horizontal position as shown in FIG. 6. Let us assume that the required loose-leaf sheets have been either removed from or inserted onto the prongs and that it is now desired to close the prongs and lock them in closed position insuring that they will not accidently become separated or opened. The prongs are closed simply by moving the actuating lever in a clockwise direction (as viewed in FIG. 6) until the trigger 12 assumes the 45 position shown in FIG. 7.

During movement of the trigger from the horizontal position to the 45 position, the body 13 of the actuator portion of the actuating lever is forcibly pivoted inside the case with its upper surface 16 slidably engaging the undersurface of the case and with the lugs 24 engaging the hinge plates. The pivot axis of the lever during this movement is defined by an imaginary line extending through the points of contact between lugs 24 and the hinge plates. This movement of the actuating lever forces the hinge plates to pivot downward through a position where they are disposed in substantially coplanar relationship. The hinge plates are subjected tosignificant compressive stress at the coplanar position causing slight but significant flexure or distortion of the case 1 as was previously mentioned. The compressive stress is released as the hinge plates move through the coplanar position whereupon the hinge plates pivot with a snap action sharply outward under the force exerted by the case returning to a semi relaxed stage until they are stopped in their outwardly bowed position as the respective ends 2a, 3a of the aligned prong pairs 2', 3 are brought into contact with each other. After the hinge plates have snapped into their outwardly bowed position, the body of the actuator portion is freely seated inside the case at about a 45 attitude as shown in FIG. 7. By freely seated it is meant that it is not uncommon to find some looseness or play in the actuating lever when it occupies this position.

With the actuating lever in the 45 position, the prong pairs 2, 3' are closed. Although in this position they are closed together relatively tightly, there is nevertheless some danger that the hinge plates may be inadvertently jarred back to their open or inwardly bowed position should the binder be accidently dropped. There is also some danger that the weight of the loose-leaf sheets held on the closed prong pairs may be sufficient to pry them slightly apart or possibly cause the hinge plates to snap back to their inwardly bowed position. The latter possibility becomes more likely when the binder is stored in inverted position such that the loose-leaf sheets hang from the prongs.

To prevent such inadvertent opening of the prongs and consequent loss of loose-leaf sheets from the binder, the prongs may be locked in closed position. Locking is accomplished simply by moving the trigger 12 inwardly through a sufficient angle beyond the 45 position shown in FIG. 7 toward the center position shown in FIG. 7b into, say, the position shown in FIG. 70. Referring now to FIG. 7c, in this wedged-in position the major portion 16a of the upper surface 16 of body 13 is in tight surface-to-surface engagement with the undersurface of the case; the remaining or minor portion 16b of upper surface 16 contacting with relatively slight pressure the undersurface of case 1; and the lugs 24 are disposed in tight engagement with the hinge plates. Thehinge plates are thereby secured in their outwardly bowed position; and thus the prong pairs 2', 3' are locked together. As shown in FIG. 7a, an imaginary line (e.g. line 40) interconnecting any point of contact between the lugs 24 and hinge plates and any point of contact between upper edge 16 of body 13 and the undersurface of case 1 extends at an upwardly inclined attitude in a direction (indicated by arrow 41) extending longitudinally outward relative to case 1. In other words, any point of contact between the major portion 16a of upper surface 16 of body 13 and the case 1 lies longitudinally outward of any point of contact between lugs 24 and outwardly bowed hinge plates 2, 3.

With thelever in the position shown in FIG. 7a or with the lever in any angular position between that shown in FIG. 7a and the center position shown in FIG. 7b the imaginary line 40 referred to above lies at an up wardly inclined attitude extending outwardly of the case. Although the aligned prong pairs are locked together when the lever is disposed at any of these angular positions, there exists a possibility that the leverv could be accidently dislodged in which event the wedged-in body 13 of the lever would fall back to the 45 position described previously. And, if the force causing such accidental dislodgement was great enough it is possible that the lever could be moved back into the horizontal position described above thus completely opening the prongs.

According to this invention, accidental dislodgement of the body 13 from its wedged-in position between the hinge plates and case can be effectively prevented by simply forcing the lever inwardly in the direction of arrow 42 past the center position shown in FIG. 7b and into the past center position shown in FIGS. 5, a and 70.

In the center position shown in FIG. 7b it will be seen the imaginary line 40 extends in a direction'perpendicular to the case. In other words, any point of contact between the major portion 16a of upper surface of body 13 and the case lies directly above or over any point of contact between lugs 24 and outwardly bowed hinge plates 2, 3. It will be recognized that maximum compressive stress is exerted on body 13 at the center position; this stress being somewhat less on either side of the center position. Therefore a relatively high force is required to be applied to the lever to move the body 13 through the center position. As a corollary, a relatively large force is required to move the lever from the past-center position back through center into a before center position. It will also be recognized that distortion or outward flaring of the end portion of the case occurs as the body is moved through its range of wedged-in positions; the greatest distortion being at the center position. This distortion or outward flaring of the end portion of the case is shown in the drawings but is enlarged beyond actual proportions for purposes of illustration.

In the past center position shown in FIG. 7c the imaginary line 40 lies at an upwardly inclined attitude in a direction (indicated by arrow 43) extending longitudinally inward relative to the case. In other words, any point of contact between the major portion 16a of upper surface 16 of body 13 and case 1 lies longitudinally inward of any point of contact between lugs 24 and the outwardly bowed hinge plates 2, 3.

With the lever in the past-center position shown in FIG. 70, the trigger 12 is disposed at the position and the section 15b of retaining member 15 is disposed in engagement with seating surface on case 1. The lever is thereby prevented from being inwardly pivoted further by an accidently applied force in the direction of arrow 43 into a position where the body 13 would cease to be wedged between the case and outwardly bowed hinge plates. Furthermore, inasmuch as the body 13 is beyond the center position a relatively large force would be required to move the body 13 back through the center position and out of wedged-in relationship between the hinge plates and case. Except by purposeful movement of the trigger 12 back through the center position and the 45-position and into the horizontal position to open the prongs, it is extremely unlikely that such a force would be accidentally applied during normal usage or even during moderate abnormal use as, for example, by dropping the binder or by suspending a relatively heavy load of loose-leaf sheets from the closed prongs. Effectively, therefore, in the past-center position of the wedged-in body 13 the lever is safely locked against accidental release to -a much greater degree than would be provided by positioning the body 13 in the center position or any ante-center position. This safety feature renders a loose-leaf ring binder constructed according to the present invention extremely valuable and advantageous as compared with heretofore known constructions including,in particular, the construction shown in previously men tioned U.S. Pat. No. 3,098,490 to Wance.

During movement of the lever through the range of angular positions where body 13 is wedged between the case and outwardly bowed hinge plates, the fulcrum points for the lever are defined by the points of contact between lugs 24 and hinge plates 2, 3. Asmentioned previously the lugs are bent relative to body 13 of the lever actuating portion. This construction achieves the proper positioning of the contact points between upper surface 16 of body 13 and case 1 relative to the-contact points between lugs 24 and hinge plates 2, 3 as previously discussed to provide the unique and novel past center safety lock feature in a ring binder constructed according to this invention.

To open the prongs, the lock is first released by moving the trigger back to its loosely seated 45 position. Then, the triggers at each end of the case are pressed into the horizontal position. Such movement causes the lifting element 19 to be pivoted into engagement with the underside of the hinge plates 2,.3 thereby moving them through the coplanar position and into the inwardly bowed position in the same manner and with the same motion as described above in connection with closing the prongs by moving the hinge plates from the inwardly bowed position to the outwardly bowed position. During movement of the trigger 12 from the 45 position to the horizontal position, the lugs 24 disengage hinge plates 2, 3 and the lever is pivoted about fulcrum points defined by the points of engagement between corner 14b joining legs 14 with the lower edge 17 of body 13 and the notches 18 in the hinge plates. The looseness or play in the lever at the 45 position is accounted for by the shifting of the lever from the fulcrum points defined by the points of engagement between lugs 24 and hinge plates 2, 3 to the fulcrum points defined by the points of engagement between corners 14b and the hinge plates 2, 3 previously described.

We claim:

1. In a loose-leaf binding mechanism whcih includes an elongated spring case, a pair of relatively stiff but resilient elongated hinge plates pivotally mounted within the case, the outer longitudinal edge of each plate defining its pivot axis with the inner longitudinal edges of the plate disposed in abutting relationship for all angular positions of the hinge plates, at least one prong on each hinge plate projecting externally of the case with each prong on one hinge plate being positioned in alignment with a prong on the other hinge plate, and actuator means for moving said hinge plates between a prong-closed position wherein each pair of aligned prongs form a substantially closed loop for retaining loose-leaf sheets and a prong-open position wherein each pair of aligned prongs are spread apart to permit insertion and removal of loose-leaf sheets, the improvement wherein the actuator means comprises:

a. a pivotally mounted lever member positioned in an opening in the hinge plates and pivotally-operated around the opening in the hinge plates;

b. hinge plate depressor means carried on said lever member for moving the hinge plates from said prong-open position to said prong-closed position upon pivoting of the lever member in one direction through a first predetermined arcuate segment of the path of movement of the lever member;

c. plate lifting means carried on said lever member for moving the hinge plates from said prong-closed position to said prong-open position upon pivoting of the lever member in the opposite direction through said first arcuate segment;

d. one portion of said lever member which portion includes lug elements being selectively movable along a second predetermined arcuate segment of the path of movement of the lever member between a first position where it is wedged tightly between the case and prong-closed hinge plates such that an imaginary line interconnecting any point of contact between said one portion and the case with any point of contact between said one portion and the hinge plates is oriented at an upwardly inclined outwardly extending attitude and a second position where it is wedged tightly between the case and prong-closed hinge plates such that said imaginary line is oriented at an upwardly inclined inwardly extending attitude, said second predetermined arcuate segment being adjacent to the said first arcuate segment and further being on the inward side of said first segment;

e. lock stop means capable of preventing pivotal movement of the lever member inwardly out of wedged-in engagement between the case and outwardly bowed hinge plates, said stop means includi. a stationary seating surface mounted on the case in the path of movement of said lever member which surface is along the centerline of the case and a substantial distance to either side of the centerline; and

ii. a retaining element mounted on said lever member for engagement along the centerline of the case and for engagement a substantial distance to either side thereof with said seating surface upon movement of said one portion of the lever member into said second wedged-in position; and

f. said case being transversely arched with the crown of the arch facing up and said one portion of the lever member including a transversely arched body conforming generally to the curvature of the case with its crown extending generally inwardly or upwardly depending on the angular position of the lever member, said body having a lower surface and a transversely arched upper surface conforming generally to the curvature of the case, said lug elements depending downwardly from the lower surface with one lug element positioned on one side of center and another lug element positioned on the other side of center with each lug element extending into engagement with one of said hinge plates, said upper surface engaging the case and the terminal ends of said lugs engaging the respective hinge plates at all wedged-in angular positions of said one portion of the lever member.

2. The improvement according to claim 1 wherein:

a. said seating surface is defined by the end of said case; and

b. said retaining element includes:

1. a first section connected to said one portion of the lever member and extending longitudinally outward relative to the case in closely spaced relationship thereto; and

2. a second section extending exteriorly of the case in substantially perpendicular relationship to the first section, said second section being engageable with the end of the case upon movement of said one portion of the lever member to said second position.

3. The improvement according to claim 1 wherein:

a. said lifting means includes a T-shaped lifting element depending from the center of said lower surface and extending through an opening formed along the interface between the inner edges of the hinge plates to engage the undersurface of each hinge plate adjacent said interface at a point located longitudinally inward of the pivot axis for said lever member during movement in said opposite direction.

4. The improvement according to claim 1 wherein:

a. said one portion of the lever member further includes a leg element depending from each end of said body, each leg element engaging a notch formed in the outer edge of the respective hinge plate.

5. The improvement according to claim 4 wherein:

a. points of engagement between the lug elements and the hinge plates define the fulcrum points for the lever member upon movement in both directions along said second predetermined arcuate segment of the path of movement of the lever member and upon movement in said one direction along said first predetermined arcuate segment; and

b. the points of engagement between said leg elements and said notches define the fulcrum points for the lever member upon movement in said oppo- 3 8 8 4,5 8 6 1 l 1 2 site direction along said first predetermined arcusaid actuator means further includes a trigger element ate segment of the path of movement of the lever forming an extension of the second section of the remember. t'aining element. 6. The improvement according to claim 5 wherein 

1. In a loose-leaf binding mechanism whcih includes an elongated spring case, a pair of relatively stiff but resilient elongated hinge plates pivotally mounted within the case, the outer longitudinal edge of each plate defining its pivot axis with the inner longitudinal edges of the plate disposed in abutting relationship for all angular positions of the hinge plates, at least one prong on each hinge plate projecting externally of the case with each prong on one hinge plate being positioned in alignment with a prong on the other hinge plate, and actuator means for moving said hinge plates between a prong-closed position wherein each pair of aligned prongs form a substantially closed loop for retaining loose-leaf sheets and a prong-open position wherein each pair of aligned prongs are spread apart to permit insertion and removal of loose-leaf sheets, the improvement wherein the actuator means comprises: a. a pivotally mounted lever member positioned in an opening in the hinge plates and pivotally-operated around the opening in the hinge plates; b. hinge plate depressor means carried on said lever member for moving the hinge plates from said prong-open position to said prong-closed position upon pivoting of the lever member in one direction through a first predetermined arcuate segment of the path of movement of the lever member; c. plate lifting means carried on said lever member for moving the hinge plates from said prong-closed position to said prongopen position upon pivoting of the lever member in the opposite direction through said first arcuate segment; d. one poRtion of said lever member which portion includes lug elements being selectively movable along a second predetermined arcuate segment of the path of movement of the lever member between a first position where it is wedged tightly between the case and prong-closed hinge plates such that an imaginary line interconnecting any point of contact between said one portion and the case with any point of contact between said one portion and the hinge plates is oriented at an upwardly inclined outwardly extending attitude and a second position where it is wedged tightly between the case and prong-closed hinge plates such that said imaginary line is oriented at an upwardly inclined inwardly extending attitude, said second predetermined arcuate segment being adjacent to the said first arcuate segment and further being on the inward side of said first segment; e. lock stop means capable of preventing pivotal movement of the lever member inwardly out of wedged-in engagement between the case and outwardly bowed hinge plates, said stop means including: i. a stationary seating surface mounted on the case in the path of movement of said lever member which surface is along the centerline of the case and a substantial distance to either side of the centerline; and ii. a retaining element mounted on said lever member for engagement along the centerline of the case and for engagement a substantial distance to either side thereof with said seating surface upon movement of said one portion of the lever member into said second wedged-in position; and f. said case being transversely arched with the crown of the arch facing up and said one portion of the lever member including a transversely arched body conforming generally to the curvature of the case with its crown extending generally inwardly or upwardly depending on the angular position of the lever member, said body having a lower surface and a transversely arched upper surface conforming generally to the curvature of the case, said lug elements depending downwardly from the lower surface with one lug element positioned on one side of center and another lug element positioned on the other side of center with each lug element extending into engagement with one of said hinge plates, said upper surface engaging the case and the terminal ends of said lugs engaging the respective hinge plates at all wedged-in angular positions of said one portion of the lever member.
 2. The improvement according to claim 1 wherein: a. said seating surface is defined by the end of said case; and b. said retaining element includes:
 2. a second section extending exteriorly of the case in substantially perpendicular relationship to the first section, said second section being engageable with the end of the case upon movement of said one portion of the lever member to said second position.
 3. The improvement according to claim 1 wherein: a. said lifting means includes a T-shaped lifting element depending from the center of said lower surface and extending through an opening formed along the interface between the inner edges of the hinge plates to engage the undersurface of each hinge plate adjacent said interface at a point located longitudinally inward of the pivot axis for said lever member during movement in said opposite direction.
 4. The improvement according to claim 1 wherein: a. said one portion of the lever member further includes a leg element depending from each end of said body, each leg element engaging a notch formed in the outer edge of the respective hinge plate.
 5. The improvement according to claim 4 wherein: a. points of engagement between the lug elements and the hinge plates define the fulcrum points for the lever member upon movement in both directions along said second predetermined arcuate segmenT of the path of movement of the lever member and upon movement in said one direction along said first predetermined arcuate segment; and b. the points of engagement between said leg elements and said notches define the fulcrum points for the lever member upon movement in said opposite direction along said first predetermined arcuate segment of the path of movement of the lever member.
 6. The improvement according to claim 5 wherein said actuator means further includes a trigger element forming an extension of the second section of the retaining element. 